Structure for continuous monitoring of shaft vibration magnitude and phase angle

ABSTRACT

Structure for and method of continuously monitoring and recording the magnitude and phase angle of vibration of a rotary shaft is disclosed. The structure includes means for integrating a vibration proportional, velocity signal to provide a sinusoidal signal having an amplitude magnitude proportional to vibration magnitude and means for rectifying and integrating the sinusoidal signal to provide a direct current signal proportional to the magnitude of vibration, structure for shaping the sinusoidial signal and subsequently differentiating it to provide relatively sharp electrical signals representing a particular angular position of vibration magnitude measurement which sharp signals are operable together with other relatively sharp electrical signals representing a predetermined angular zero position on the rotating shaft obtained from a pickup probe mechanically associated with the shaft and timing pulse amplifying and shaping structure, to set and reset a multivibrator and means for integrating the output of the multivibrator to provide a direct current signal proportional to the relative phase angle of the vibration magnitude recorded. A zero adjust structure and method is provided for both of the vibration magnitude and phase angle monitoring and recording means.

SRi

llnitedStaEs Simpkin et al.

51 Aug. 29, 1972 [54] STRUCTURE FOR CONTINUOUS Primary Examiner-RichardC. Queisser MONITORING OF SHAFT VIBRATION Assistant ExaminerJohn B.Beauchamp MAGNITUDE AND PHASE ANGLE Attorney-Whittemore, l-lulbert andBelknap [72] Inventors: Lawrence J. Simpkin, Dearbom Heights; Richard M.Srodawa, [57] ABSIMCT Detroit, Mich. Structure for and method ofcontinuously monitoring and recording the magnitude and phase angle ofvibra- [73] Asslgnee pig: Edison Company tion of a rotary shaft isdisclosed. The structure introlt 1c cludes means for integrating avibration proportional,

[22] Filed: Aug. 10, 1970 velocity signal to provide a sinusoidal signalhaving an amplitude magnitude proportional to vibration mag- [211APPLNO" 6243l nitude and means for rectifying and integrating thesinusoidal signal to provide a direct current signal pro- [52] US. Cl..73/462, 73/714 porlional t0 the magnitude of vibration, structure for[51] Int.Cl. ..G01m 1/22 h pi g the sinusoidial ign and subsequently[58] Field of Search ..73/67, 71.2, 71.4, 462 ferentiating it to providerelatively sharp electrical signals representing a particular angularposition of 5 R f n e Cit d vibration magnitude measurement which sharpsignals are operable together with other relatively sharp elec- UNITEDSTATES PATENTS trical signals representing a predetermined angular3,201,996 8/1965 Silvia ..73/67 x 9 i l a 2,783,648 3/1957 Stovall, Jr.et al. ..73/462 l P mechmlcaily Shaft 3 048 041 8/1962 Trimble ..73/462and mung Pulse PP and shapmg stPlcmrea 72 11/1969 Blackmer 73/71 4 setand reset a multivibrator and means for mtegratmg the output of themultivibrator to provide a direct cur- 2,363,373 11/1944 Werner..73/71.4 X rent g 31 proportion 81 to the relative phase angle ofFOREIGN ATENT R APPLICATIONS the vibration magnitude recorded. A zeroadjust structure and method is provided for both of the vibration1,129,477 10/1968 Great Bntam ..73/462 magnitude and phase anglemonitoring and recording means.

- 7 Claims, 3 Drawing figures B 1 "1 l FREQUENCY 1 16 COMfEKYon l 16 r"w l '72 l l L ANDN l 36 l l RECORDER I VIBRATION i l l l AMPLIFIER I il I i 42 I 51161 l 24 i \32 -RECTIFIER l l 34 l l l I I SELECTOR L5Q l li SWITCH l l 46 1 h l TIMING PULSE PUlSE l AMPLIFI R GENERATOR 1 I ANDSHAPEF I L E I V 1a REGULATOR POWER I60 SUPPLY Patented Aug. 29, 1972 2Sheets-Sheet 1 "I I l I FREQUENCY I Ii I ER -F0R I I I I L AND N I I IRECDRDER I I VIBRATION I I I I I AMPLIFIER I I I I I 38 42 I SELECTORSWITCH I I I 32 I FLIP I I RECTIFIER I 34\ I I I FLOP I I I SELECTOR I I50 \44 I I SWITCH I I 46 I I I I TIMIN I. pu .PULSE I AMPLIFIERGENERATOR I REGULATOR POWER ./%6O

SUPPLY FIG.2.

INVENTOR LAWRENCE J. SIMPKI'N RICHARD M. SRODAWA BY wlifimm Eli/4y;

Patented Aug. 29, 1972 2 Sheets-Sheet 2 INVENTOR.

LAWRENCE SI MPKI N M RIC HARD M-SRODAWA STRUCTURE FOR CONTINUOUSMONITORING OF SHAFT VIBRATION MAGNITUDE AND PHASE ANGLE BACKGROUND OFTHE INVENTION 1. Field of the Invention The invention relates tomonitoring equipment for rotating shafts and refers more specifically.to structure for and a method of continuously monitoring the magnitudeof vibration of a rotating shaft and the phase angle of the monitoredvibration magnitude.

2. Description of the Prior Art In the past, vibration magnitude sensingand the sensing of the phase angle at which the vibration magnitudesensed occurred has been a relatively complicated and often inefficientprocedure. Prior structures for vibration magnitude and phase anglesensing has often been capable of providing only discrete separateindications rather than a continuous record of vibration magnitude andphase angle of the vibration magnitude over an extended period. Theequipment for performing such measurements has also been expensive andtherefore prohibitive in many instances.

The continuous monitoring of vibration magnitude and phase angle isdesirable to aid in the diagnosis of the cause of the vibration; forexample, a history of vibration magnitude and the phase angle at whichthe vibration magnitude isrecorded is useful in determining continuedwear of a rotating shaft or the like since the phase angle in such caseswill gradually change. The continuous recording of the vibrationmagnitude and phase angle at which the vibration magnitude occurs istherefore extremely desirable in analyzing the operation of a rotatingshaft over an extended period.

SUMMARY OF THE INVENTION In accordance with the invention, there isprovided a circuit for a method of monitoring the magnitude of vibrationof a rotating shaft and the relative phase angle of the vibration of therotating shaft over an extended period of time in conjunction with oneor more vibration pickups mounted on a member vibrating in accordancewith the vibration of the rotating shaft and timing signal producingmeans operably associated with the rotating shaft to provide a phaseangle reference signal. The monitored vibration magnitude and phaseangle is continuously recorded to provide a permanent record thereofwhereby shaft operation may be diagnosed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of vibrationmagnitude and phase angle monitoring and recording structure constructedin accordance with the invention.

FIG. 2 is a pictorial representation of the timing pulse generatingstructure and the vibration sensing and transducing structure of thestructure of the invention illustrating their application to a rotatingshaft, the vibration of which is to be monitored thereby.

FIG. 3 is a schematic diagram of the electric circuit, for providing adirect current signal proportional to vibration magnitude and the phaseangle at which the vibration magnitude monitored occurs continuously, ofthe structure of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown best in FIG. 1, thestructure 8 for continuously monitoring the magnitude of vibration ofthe vibrating shaft 22 and the phase angle at which the vibration occursincludes sensing structure l0comprising one or more vibration pickupstructures 12 and a timing signal pickup structure 14, a recording unit16 and an electronic circuit 18 for receiving vibration signals from thevibration pickup structures 12 through the recording unit 16 and forreceiving a timing signal from the timing signal pickup structure 14 andfor returning a direct current signal proportional to the magnitude ofthe vibration sensed and a direct current signal proportional to thephase angle of the vibration signal sensed to the recording unit 16. Therecording unit is operable to cyclically record the magnitude ofvibration and the phase angle at which the vibration occurred for eachof a plurality of vibration pickup structures 12 in sequence.

As shown best in FIG. 2, the vibration pickup structures 12 may besecured to collars 20 mounting the shaft 22, the vibration of which isto be monitored, in bearings or the like. The vibration pickupstructures 12 may be electro-magnetic devices constructed and energizedto provide an output over conductors 24 to the recording unit 16 whichis proportional to the velocity of the portion of the collars 20 towhich the vibration pickup structures 12 are secured.

Piezoelectric crystal devices for providing an electrical output signalin proportion to the pressure applied thereto or other sensitiveaccelerometer devices may be used to provide the output signal ontheconductors 24 proportional to the velocity of movement of the portionof the collars 20. In addition, the vibration pickup structures 12 maybe positioned at a plurality of separate linearly and angularly spacedpositions along the shaft 22, as desired.

The timing signal pickup structure 14, as shown best in FIG. 2, includesa photoelectric device 26 positioned adjacent the shaft 22 inconjunction with a portion of the shaft 22 which has been painted toprovide a sharp line 28 of contrasting color. Thus, as the shaft 22rotates when the sharp line between the contrasting colors on the shaft22 passes the photoelectric device 26, an electric signal due to adifference in the reflected light on opposite sides of the line 28 willbe provided on the conductor 30. The signal on the conductor 30 may beconsidered as a zero phase angle reference signal.

The recording unit 16 is a purchased four-channel Leeds & Northruprecording unit. The recording unit 16 may of course be any othercommercially available unit which will provide multiple-channelrecording and which includes, along with a recorder 31, as shown in FIG.1, a first selector switch 32 and a second selector switch 34 cooperableto first receive a vibration magnitude signal from one of the vibrationpickup structures l2 and to subsequently record the vibration magnitudeand the phase angle of the vibration magnitude sensed by the firstvibration magnitude pickup structure l2 and to then select a second ofthe vibration magnitude pickup structures 12 to record the magnitude ofvibration from the second vibration magnitude pickup structure and thephase angle thereof and to continue such selecting and recording of thedifferent vibration pickup structures 12 until the vibration magnitudeand phase angle monitored by the last vibration magnitude pickupstructure 12 is recorded and then to start over again recording themagnitude and phase angle of the shaft vibration associated with thefirst vibration magnitude pickup structure 12.

With the particular Leeds & Northrup recording unit 16, magnitude ofvibration and phase angle of the vibration monitored by a singlevibration pickup structure has been recorded every fifteen seconds sothat with the four vibration magnitude pickup structures illustrated,each vibration magnitude and phase angle was monitored once every minuteand the recording continued over an extended period.

The vibration magnitude and phase angle signal producing circuit 18,shown best in FIG. 3, includes a vibration magnitude signal producingportion 36 and a phase angle signal producing portion 38. The vibrationmagnitude signal producing portion 36 includes the frequency compensator40, the vibration magnitude amplifier 42 and the rectifier 44. The phaseangle signal producing portion 38 of the circuit 18 includes the timingpulse amplifier and shaper 46, the pulse generator 48 and the flip-flop50.

As shown better in FIG. 3, the frequency compensator 40 of the portion38 of the circuit 18 is an integrating circuit including the resistor 52and the capacitor 54. The frequency compensator 40 is operable tointegrate the velocity signal provided from a vibration pickup structure12 through the recording unit selector switch 32 from plug 56 and toprovide a substantially sinusodial signal therefrom, the magnitude ofwhich is proportional to the magnitude of vibration of the shaft 22 atthe position monitored by the vibration pickup structure 12, whichsinusodial signal is applied to the vibration amplifier 42.

The vibration amplifier 42 is a standard operational amplifier operableto take an extremely small sinusodial signal and to provide a largersinusodial signal output therefrom, the magnitude of which is againproportional to the magnitude of the monitored shaft vibration.Resistors 58, 60, 62 and 64 are standard input, internal balancing,output and feedback resistors in the circuit of the operationalamplifier 66 and will not therefore be considered in detail herein.Capacitors 68 and 70 are similarly standard components of operationalamplifiers such as 66 and will therefore not be considered in detail.

Resistors 72 and 74 are input resistors for the other side of theoperational amplifier 66 and in conjunction with the voltage divider 76including resistors 78 and 80 and the potentiometer 82 having the wiperarm 84 in series with the resistor 86 provides a zero vibrationmagnitude adjust circuit for the operational amplifier 66. Thus, thewiper arm 84 may in operation be positioned to provide a zero outputfrom the operational amplifier 66 when the signal from the pickupstructure 12 indicates that the vibration magnitude of the shaft 22 iszero.

The amplified sinusoidal output signal from the operational amplifier 66is rectified through the rectifier 88 and is subsequently integratedthrough the averaging circuit including the resistor 90 and thecapacitor 92 to provide a direct current output signal across theselected portion of the potentiometer 94 chosen by the position of thewiper arm 96 associated therewith, the magnitude of which isproportional to the vibration of the shaft 22 at the vibration pickupstructure 12. As indicated previously, this signal is passed throughselector switch 34 in recording unit 16 to the recorder 31 in recordingunit 16 for sequential recording in one of the channels thereof.

The sinusoidal signal from the operational amplifier 66 is furtherpassed to the pulse generator 48 of the phase angle monitoring portion38 of the circuit 18. The pulse generator 48, as shown in F IG. 3,includes an operational amplifier 98 having an in put resistance 100associated with the capacitor 102, a second input resistance 104 for theopposite side thereof which as shown is connected to the ground and anoutput circuit 106. Operational amplifier 98 again is a conventionalcircuit and includes the usual feedback and other circuit componentswhich are known to those in the art. The output signal from theoperational amplifier 98 is substantially a square wave signal at thefrequency of the sinusoidal input signal thereto. The square wave signalfrom the operational amplifier 98 is differentiated in thedifferentiating portion 108 of the pulse generator 48 which includes thecapacitor 110 and the resistor 112 to provide a series of positive andnegative going spike-like signals to the flip-flop 50. The positivespikes are substantially synchronized with the initiation of thepositive portion of the vibration magnitude signals.

The timing pulse amplifier and shaper 46 of the portion 38 of thecircuit 18 receives a pulse from the light sensitive timing signalpickup structure 14 through the plug 114 in FIG. 3 at pin B each timethe line 28 on the shaft 22 rotates past the signal pickup structure 14whereby the light reflected into the pickup structure 14 is variedsharply. The timing signal thus generated is passed to the operationalamplifier 116 through the capacitor 118 and across the usual inputresistance 120. Again, the resistors 122, 124, 126 and 128 and thecapacitors 130 and 131 associated with the operational amplifier 116 areconventional and will not be considered in detail herein.

It will be noted, however, that the resistor 128 is bypassed by voltagelimiting structure 130 whereby the output of the amplifier 116 isclipped to provide a substantially square wave output to thedifferentiating structure including the resistor 132 and capacitor 134which receive the output from the amplifier 116. The differentiatedsquare wave passed through the capacitor 134 and across the resistor 132is thus also passed to the flip-flop 50 and includes positive andnegative spikes, the positive spikes of which are substantiallysynchronized with the rotation of the shaft 22 since they are ultimatelyproduced as a result of the line 28 on shaft 220.

The flip-flop 50 which is actually a dual NOR gate flip-flop issensitive only to positive signals. Thus, the positive spikes ultimatelyproduced from the timing signal pickup structure 14 is operable toprovide an output from the lower portion of the flip-flop 50 on theconductor 136 and the positive spike from the operational amplifier 98developed ultimately from the magnitude of vibration pickup structure 12is operable to cut the signal from the lower portion of the flip-flop 50on conductor 136 off at a subsequent time during the same revolution ofthe shaft 22.

The signal on the conductor 136 will thus be a square wave having apulse width proportional to the phase angle difference between thereference phase angle established by the line 28 on the shaft 22 and thephase angle determined by the time of occurrence of the positive spikeultimately produced by the vibration.

The square wave on the conductor 136 is then averaged through theresistor 138 and across capacitor 140 to provide a direct current signalacross the voltage divider 142 including the resistor 144 and thepotentiometer 146 which includes the variable wiper arm 148, themagnitude of which represents the phase angle of the vibration magnitudemonitored. This phase angle signal is passed to the recording unit 16through the recording unit plug 56 for recording in conjunction with themagnitude of vibration signal as previously indicated.

Again, a voltage divider 150 including resistances 152 and 154, andpotentiometer 156 including the wiper arm 158 is provided in conjunctionwith the voltage divider 142 to provide zero adjust structure, wherebythe integrated output signal from' the flip-flop 50 will be zero whenthe phase angle of the vibration magnitude sensed is exactly the same asthe reference phase angle determined by the line 28.

The circuit 18 is completed by the power supply 160. Power supply 160 isconventional and includes the transformers 162 and 164 which are fedfrom a usual l-volt, 60-cycle alternating current supply through plug166 and which feed the bridge rectifiers 168 and 170. Rectifier 170provides a positive five-volt output for the timing signal pickupstructure 14 through the plug 114. Rectifier 168 provides positive 12,positive 3, negative 6 and negative 12-volt output signals which arefiltered by capacitor means 172, 174, 176,178, 180, 182 and 184 inconjunction with resistors 186, 188, 190, 192, 194 and 196. The voltagesfrom the rectifier 168 are regulated by the Zener diodes 198 and 200 inconjunction with the transistors 202 and 204 connected as shown in FIG.3.

Thus, in overall operation of the structure for and method of continuousmonitoring of shaft vibration magnitude and phase angle in accordancewith the method of the invention, the vibration magnitude pickupstructures 12 are secured to structure such as the collar associatedwith the shaft 22 so that they vibrate in accordance with the vibrationof the shaft 22. The timing input pickup structure 14 is positionedadjacent the rotary shaft 22 having the sharp demarcation line 28between contrasting colored surfaced such as black and white surfacesand the shaft 22 is rotated As the shaft rotates, the recording unit 16,through selector switch 32, first selects one of the vibration magnitudepickup structures 12 for monitoring along with the timing signal pickupstructure 14. The velocity signal from the vibration pickup structure 12is integrated in the frequency compensator structure 140, is amplifiedin the vibration amplifier 42 which has previously been zeroed by thestructure associated with the voltage divider 76. The amplifiedsinusoidal wave from the amplifier 42 which is proportional in magnitudeto the vibration of the shaft 22 is then rectified and integrated toprovide a direct current signal proportional to the magnitude of thevibration of the shaft 22 at the vibration pickup structure 12, whichsignal is presented to the selector switch 34 in the recording unit 16for recording on recorder 31.

During the rotation of the shaft 22, the line 28 between the contrastinglight reflecting surfaces on the shaft 22 passes the photoelectricdevice 26 to provide an electrical timing signal, which signal isamplified and shaped in the timing pulse amplifier and shaper 46 and ispresented to the flip-flop 50 to cause the flip-flop 50 to provide anoutput signal to the selector switch 34 from one side thereof of aregulated magnitude.

During the rotation of the shaft 22, the amplified sinusoidal signalhaving a magnitude proportional to the magnitude of the vibration ofshaft 22 at the position of the vibration pickup structure 12 is alsopassed to the pulse generator 48 which squares the sinusoidal wave shapeand provides a series of spike signals therefrom by integration of thesquare wave signal. The positive spike signals are fed to the flip-flop50 to stop the output from the one side thereof. Thus, the output fromthe flip-flop 50 is proportional to the phase angle difference betweenthephase angle of the line 28 and the phase angle of the sinusoidalsignal proportional to the magnitude of the vibration of the shaft 22.

The signal from the one side of the flip-flop 50 is then integrated toprovide an output signal across the voltage divider 142 which is adirect current signal proportional to the indicated phase angledifference. The signal from the flip-flop 50 is compensated by thestructure associated with the voltage divider to provide a zero outputwhen the phase angle indicated above is zero.

The vibration magnitude signal and the phase angle signals from therectifier 44 and the flip-flop 50 are sequentially passed to therecording portion of the recording structure 16 by the selector switch34.

Subsequent operation of the structure 8 will be in exact repetition ofthe above indicated operation except the selector switch 32 willsequentially select the vibration magnitude pickup structures 12 insequence and then start over again with the .initially selectedvibration magnitude pickup structure 12. Such operation will continueuntil the structure 8 is deenergized to provide a continuous graph ofthe vibration magnitude and phase angle of the vibration of shaft 22 atvarious locations therealong. As indicated above, such information isparticularly useful in monitoring the long term operation of shaft 22and in diagnosing the causes of the vibration of the shaft 22. Also,such information may be used with known computer techniques forproviding balancing weights to remove the vibration from the shaft 22,if desired.

While one embodiment of the present invention has been considered indetail, it will be understood that other modifications and embodimentsare contemplated. It is the intention to include all modifications andembodiments of the invention as are defined by the appended claimswithin the scope of the invention.

What we claim as our invention is:

1. Structure for continuously monitoring vibration of an installedrotating shaft over a prolonged period comprising a first probe operablyassociated with the shaft for developing a sinusoidal electrical signalthe amplitude of which is proportional to the velocity of radialmovement of the shaft at the first probe in the direction of the firstprobe, a first operational amplifier connected to the first probe forreceiving and amplifying the developed signal from the first probe, arectifier connected in series with the first operational amplifier forrectifying the output thereof, an integrating circuit connected to therectifier for integrating the rectified sinusoidal output from the firstoperational amplifier, a first variable resistance connected to theintegrating circuit for receiving the output thereof, means for tappinga predetermined portion of the direct current output signal from thefirst variable resistance and means for recording the portion of thedirect current output from the first variable resistance as a directmeasure of shaft vibration magnitude, a second operational amplifierconnected to receive the sinusoidal signal output of the firstoperational amplifier and providing a square wave output therefrom, adifferentiating circuit connected to receive the square wave outputsignal of the first operational amplifier and to provide a pulsed outputin response thereto, a second probe positioned adjacent the shaft, meansfor providing a pulse of electrical energy in the second probe each timethe shaft completes a rotation relative to the second probe, 21 thirdoperational amplifier connected to the second probe for sensing thepulses of electrical energy produced by the second probe and providingan output signal synchronized with the rotation of the shaft, adifferentiating circuit for receiving the output signal from the thirdoperational amplifier and providing a pulsed output in response thereto,a dual NOR gate flip-flop circuit connected to receive thedifferentiated square wave signal from the second operational amplifierand the differentiated signals from the third operational amplifier sothat one side of the flip-flop circuit provides an output signal betweenthe time a signal is provided at the one side of the flipfiop circuitfrom the third operational amplifier and the time a signal is providedat the flip-flop circuit on the other side thereof from the secondoperational amplifier, means for integrating the output signal from theone side of the flip-flop circuit to provide a direct current signalproportional thereto, a variable resistance for receiving the integratedoutput signal from the one side of the flip-flop circuit and means fortapping off a portion of the direct current signal from the secondvariable resistance and for recording the portion of the signal from thesecond variable resistor as a direct indication of the phase angle ofthe vibration of the shaft.

2. A plurality of structures as set forth in claim 1 positioned inspaced apart locations longitudinally of the shaft whereby continuousrecording of the magnitude of shaft vibration and phase angle of theshaft vibration may be simultaneously recorded at different points alongthe shaft over prolonged periods.

3. Structure as set forth in claim 1 wherein the signal from the firstprobe is fed into one side of the first operational amplifier, andfurther including a voltage divider, a bias power supply connectedacross the voltage divider and means for connecting a variable point ofthe voltage divider to the other side of the first operational amplifierwhereby the output of the first operational amplifier may be reduced tozero with no input signal to the first operational amplifier from thefirst probe.

4. Structure as set forth in claim 1 and further including a voltagedivider, a bias power supply connected across the voltage divider, meansfor connecting a variable point on the voltage divider between theintegrating means receiving the output from the one side of theflip-flop circuit and the second variable resistor whereby the outputsignal of the flip-flop circuit to the voltage divider can be maintainedat zero with a zero input to the one side of the flip-flop circuit.

5. Structure as set forth in claim 1 wherein the first probe is anelectromagnetic velocity sensitive probe secured to a mounting bearingfor the shaft.

6. Structure as set forth in claim 1 wherein the second probe is a lightsensitive probe and means are provided on the shaft adjacent the secondprobe for abruptly changing the light reflective qualities of the shaftat one location around the circumference thereof.

7. A plurality of structures for continuously monitoring vibration of aninstalled rotating shaft at a plurality of locations along the lengththereof over a prolonged period each comprising a first electromagneticvelocity sensitive probe secured to a mounting bearing for the shaft fordeveloping a sinusoidal electrical signal the amplitude of which isproportional to the velocity of radial movement of the shaft at thefirst probe in the direction of the first probe, a first operationalamplifier connected to the first probe for receiving and amplifying thedeveloped signal from the first probe at one side thereof, a firstvoltage divider, a bias power supply connected across the first voltagedivider and means the connecting a variable point of the first voltagedivider to the other side of the first operational amplifier, wherebythe output of the first operational amplifier may be reduced to zerowith no input signal to the first operational amplifier from the firstprobe, a rectifier connected in series with the first operationalamplifier for rectifying the output thereof, an integrating circuitconnected to the rectifier for integrating the rectified sinusoidaloutput from the first operational amplifier, a first variable resistanceconnected to the integrating circuit for receiving the output thereof,means for tapping off a predetermined portion of he direct currentoutput signal from the first variable resistance and means for recordingthe portion of the direct current output from the first variableresistance as a direct measure of shaft vibration magnitude, a secondoperational amplifier connected to receive the sinusoidal signal outputof the first operational amplifier and providing a square wave outputtherefrom, a differentiating circuit connected to receive the squarewave output signal of the first operational amplifier and to provide apulsed output in response thereto, a second light sensitive probepositioned adjacent the shaft, means for abruptly changing the lightreflective qualities of the shaft at one location around thecircumference thereof for providing a pulse of electrical energy in thesecond probe each time the shaft completes a rotation relative to thesecond probe, a third operational amplifier connected to the secondprobe for sensing the pulses of electrical energy produced by the secondprobe and providing an output signal synchronized with the rotation ofthe shaft, a differentiating circuit for receiving the output signalfrom the third operational amplifier and providing a pulsed output inresponse thereto a dual NOR gate flip-flop circuit connected to receivethe differentiated square wave signal from the second operationalamplifier and the differentiated signals from the third operationalamplifier so that one side of the flip-flop circuit pro vides an outputsignal between the time a signal is provided at the one side of theflip-flop circuit from the third operational amplifier and the time asignal is provided at the flip-flop circuit on the other side thereoffrom the second operational amplifier, means for integrating the outputsignal from the one side of the flipflop circuit to provide a directcurrent signal proportional thereto, a second variable resistance forreceiving the integrated output signal from the one side of theflip-flop circuit, a second voltage divider, a bias power supplyconnected across the second voltage divider, means for connecting avariable point on the second voltage divider between the integratingmeans receiving the output from the one side of the flip-flop circuitand the second variable resistor whereby the output signal of theflip-flop circuit to the second voltage divider can be maintained atzero with a zero input to the one side of the flip-flop circuit, andmeans for tapping off a portion of the direct current signal from thesecond variable resistance and for recording the portion of the signalfrom the second variable resistor as a direct indication of the phaseangle of the vibration of the shaft.

1. Structure for continuously monitoring vibration of an installedrotating shaft over a prolonged period comprising a first probe operablyassociated with the shaft for developing a sinusoidal electrical signalthe amplitude of which is proportional to the velocity of radialmovement of the shaft at the first probe in the direction of the firstprobe, a first operational amplifier connected to the first probe forreceiving and amplifying the developed signal from the first probe, arectifier connected in series with the first operational amplifier forrectifying the output thereof, an integrating circuit connected to therectifier for integrating the rectified sinusoidal output from the firstoperational amplifier, a first variable resistance connected to theintegrating circuit for receiving the output thereof, means for tappinga predetermined portion of the direct current output signal from thefirst variable resistance and means for recording the portion of thedirect current output from the first variable resistance as a directmeasure of shaft vibration magnitude, a second operational amplifierconnected to receive the sinusoidal signal output of the firstoperational amplifier and providing a square wave output therefrom, adifferentiating circuit connected to receive the square wave outputsignal of the first operational amplifier and to provide a pulsed outputin response thereto, a second probe positioned adjacent the shaft, meansfor providing a pulse of electrical energy in the second probe each timethe shaft completes a rotation relative to the second probe, a thirdoperational amplifier connected to the second probe for sensing thepulses of electrical energy produced by the second probe and providingan output signal synchronized with the rotation of the shaft, adifferentiating circuit for receiving the output signal from the thirdoperational amplifier and providing a pulsed output in response thereto,a dual NOR gate flip-flop circuit connected to receive thedifferentiated square wave signal from the second operational amplifierand the differentiated signals from the third operational amplifier sothat one side of the flip-flop circuit provides an output signal betweenthe time a signal is provided at the one side of the flip-flop circuitfrom the third operational amplifier and the time a signal is providedat the flip-flop circuit on the other side thereof from the secondoperational amplifier, means for integrating the output signal from theone side of tHe flip-flop circuit to provide a direct current signalproportional thereto, a variable resistance for receiving the integratedoutput signal from the one side of the flip-flop circuit and means fortapping off a portion of the direct current signal from the secondvariable resistance and for recording the portion of the signal from thesecond variable resistor as a direct indication of the phase angle ofthe vibration of the shaft.
 2. A plurality of structures as set forth inclaim 1 positioned in spaced apart locations longitudinally of the shaftwhereby continuous recording of the magnitude of shaft vibration andphase angle of the shaft vibration may be simultaneously recorded atdifferent points along the shaft over prolonged periods.
 3. Structure asset forth in claim 1 wherein the signal from the first probe is fed intoone side of the first operational amplifier, and further including avoltage divider, a bias power supply connected across the voltagedivider and means for connecting a variable point of the voltage dividerto the other side of the first operational amplifier whereby the outputof the first operational amplifier may be reduced to zero with no inputsignal to the first operational amplifier from the first probe. 4.Structure as set forth in claim 1 and further including a voltagedivider, a bias power supply connected across the voltage divider, meansfor connecting a variable point on the voltage divider between theintegrating means receiving the output from the one side of theflip-flop circuit and the second variable resistor whereby the outputsignal of the flip-flop circuit to the voltage divider can be maintainedat zero with a zero input to the one side of the flip-flop circuit. 5.Structure as set forth in claim 1 wherein the first probe is anelectromagnetic velocity sensitive probe secured to a mounting bearingfor the shaft.
 6. Structure as set forth in claim 1 wherein the secondprobe is a light sensitive probe and means are provided on the shaftadjacent the second probe for abruptly changing the light reflectivequalities of the shaft at one location around the circumference thereof.7. A plurality of structures for continuously monitoring vibration of aninstalled rotating shaft at a plurality of locations along the lengththereof over a prolonged period each comprising a first electromagneticvelocity sensitive probe secured to a mounting bearing for the shaft fordeveloping a sinusoidal electrical signal the amplitude of which isproportional to the velocity of radial movement of the shaft at thefirst probe in the direction of the first probe, a first operationalamplifier connected to the first probe for receiving and amplifying thedeveloped signal from the first probe at one side thereof, a firstvoltage divider, a bias power supply connected across the first voltagedivider and means for connecting a variable point of the first voltagedivider to the other side of the first operational amplifier, wherebythe output of the first operational amplifier may be reduced to zerowith no input signal to the first operational amplifier from the firstprobe, a rectifier connected in series with the first operationalamplifier for rectifying the output thereof, an integrating circuitconnected to the rectifier for integrating the rectified sinusoidaloutput from the first operational amplifier, a first variable resistanceconnected to the integrating circuit for receiving the output thereof,means for tapping off a predetermined portion of the direct currentoutput signal from the first variable resistance and means for recordingthe portion of the direct current output from the first variableresistance as a direct measure of shaft vibration magnitude, a secondoperational amplifier connected to receive the sinusoidal signal outputof the first operational amplifier and providing a square wave outputtherefrom, a differentiating circuit connected to receive the squarewave output signal of the first operational amplifier and to provide apulsed output in response thereto, a second light sensitive probepositioned adjacent the shaft, means for abruptly changing the lightreflective qualities of the shaft at one location around thecircumference thereof for providing a pulse of electrical energy in thesecond probe each time the shaft completes a rotation relative to thesecond probe, a third operational amplifier connected to the secondprobe for sensing the pulses of electrical energy produced by the secondprobe and providing an output signal synchronized with the rotation ofthe shaft, a differentiating circuit for receiving the output signalfrom the third operational amplifier and providing a pulsed output inresponse thereto, a dual NOR gate flip-flop circuit connected to receivethe differentiated square wave signal from the second operationalamplifier and the differentiated signals from the third operationalamplifier so that one side of the flip-flop circuit provides an outputsignal between the time a signal is provided at the one side of theflip-flop circuit from the third operational amplifier and the time asignal is provided at the flip-flop circuit on the other side thereoffrom the second operational amplifier, means for integrating the outputsignal from the one side of the flip-flop circuit to provide a directcurrent signal proportional thereto, a second variable resistance forreceiving the integrated output signal from the one side of theflip-flop circuit, a second voltage divider, a bias power supplyconnected across the second voltage divider, means for connecting avariable point on the second voltage divider between the integratingmeans receiving the output from the one side of the flip-flop circuitand the second variable resistor whereby the output signal of theflip-flop circuit to the second voltage divider can be maintained atzero with a zero input to the one side of the flip-flop circuit, andmeans for tapping off a portion of the direct current signal from thesecond variable resistance and for recording the portion of the signalfrom the second variable resistor as a direct indication of the phaseangle of the vibration of the shaft.